Batteries are known and used as a source of power. Typically, a battery cell (or battery) includes an anode and a cathode and one or more reactants at the anode/cathode. During the reaction, an electric voltage is formed by the reaction, which may be collected and used as a power source.
One type of battery that is known involves using lithium as the anode. Such batteries are often referred to as “lithium” batteries. This reaction of lithium may be summarized as follows:Li→Li++e−In this reaction, lithium metal is oxidized to the lithium ion. A variety of different types of cathodes may be used in conjunction with the lithium anode. One typical cathode involves using water as the reactant at the cathode, thereby producing hydrogen gas and hydroxide. This cathode reaction may be summarized as follows:H2O+e−→½H2+OH−Thus, the overall reaction of this type of lithium battery may be summarized as follows:Li+H2O→½H2+OH−+Li+orLi+H2O→½H2+LiOHAs lithium is consumed at the anode, water is consumed at the cathode while hydrogen is evolved and lithium hydroxide is produced.
The above-recited lithium batteries have been studied for use in underwater or undersea applications. As noted above, the reaction involves consuming water (H2O) at the cathode. Accordingly, seawater or even freshwater may be the water source for the reaction. Such types of batteries are especially desirable to unmanned undersea vehicles, which are useful for data gathering, taking measurements under the ocean, etc. Advantages of using these types of lithium batteries in undersea applications are that they are lightweight, provide natural buoyancy (as lithium is lighter than water) and are relatively silent in their operation.
There are, however, some known disadvantages associated with the use of lithium batteries in underwater applications. The lithium battery includes a lithium ion-conductive membrane. This membrane is used as the membrane that separates the anode from the water in the cathode. This lithium ion-conductive membrane is designed to allow lithium ions to pass through the membrane (e.g., from the anode to the cathode). Such lithium ion-conductive membranes contain a quantity of lithium ions. Such lithium ion-conductive membranes are known to fail, over time, when they are contacted with sodium ions (which are found, in significant quantities, in seawater). More specifically, the mobile lithium ions in the ion-conductive lithium membrane may exchange with the sodium ions in an aqueous (seawater) phase. This exchange can be undesirable because the lattice structure of the ion-conductive membrane may expand as the larger sodium ions replace the smaller lithium ions in the lattice. This expansion may result in distortion and stress of the ion-conductive membrane which may result in fracture and ultimately failure of the battery. This problem is especially prevalent where seawater is used as the water source because this water quantity already contains a significant quantity of sodium ions dissolved therein.
Accordingly, there is a need in the art for a new type of lithium battery that will not have the lithium ion-conductive membrane be fouled by sodium ions dissolved in seawater. Such a battery is disclosed herein.